The present disclosure relates to polycarbonate articles (e.g. films, powders, fibers, etc.) that are substantially cross-linked generally throughout their thickness, and/or have good scratch resistance. The articles are formed from a cross-linkable polycarbonate resin containing a photoactive group derived from a benzophenone. Upon exposure to ultraviolet radiation, the photoactive group will crosslink with itself and/or with other polymeric base resins also present, improving overall chemical resistance, flame retardance, and other characteristics. Also included are processes for the formation of such articles and compositions containing the cross-linkable polycarbonate resins.
Polycarbonates (PC) are thermoplastic resins with desirable properties such as high impact strength and toughness, transparency, and heat resistance. However, they also drip when exposed to a flame, and this behavior worsens as wall thickness decreases. This is undesirable for applications requiring V0 or 5VA performance.
They can also be marred or degraded by common solvents, especially when their flow rate is increased by reducing the molecular weight of the polymer. Thin structures also typically have a high built-in strain. As the use temperature of such thin structures nears the glass transition temperature, the thin structure can lose its shape due to release of the strain. It would be desirable to produce articles which have thin walls, yet retain their shape and have improved flame retardance properties and improved chemical resistance.
Polycarbonates are also easy to scratch. One way to achieve better scratch resistance is to post-coat polycarbonate components with a coating that when cured provides the desired performance. The coating forms a bonded hard layer on the surface and has a thickness typically from 3 micrometers (μm) to 18 μm. Examples of such hard coats include acrylate hard coats that are either ultraviolet (UV) or thermally curable, silicone hard coats with acrylate primers, polyurethane hard coats, and melamine hard coats. However, an extra post-production coating step is required to apply and cure these coatings to the polycarbonate film surface. It would be desirable to eliminate this extra step.